1. Field of the Invention
The present invention relates to arthroscopic surgical procedures for ligament reconstuction and particularly to apparatus and a procedure for isometrically locating either an anterior or posterior cruciate ligament femoral and tibial points of attachment.
2. Prior Art
In anterior and posterior ligament replacement surgery both ligament tension and positioning of that ligament between tibial and femoral surfaces must be optimumized for a successful surgery. Prior to the present invention such positioning involved a surgeon utilizing a fluroroscopic monitor or visually forming a tunnel to pass through the approximate ruptured ligament tibial and femoral points of origin, and attaching a ligament therein to test for correct isometry. An example of such procedure is shown in a patent to Daniel, et al., U.S. Pat. No. 4,712,542. If the ligament positioning was found not to be isometrically correct the tunnel had to be altered or reformed until correct isometry was obtained. Essentially, a trial and error procedure with the surgeon's skill determining the outcome.
Unlike the trial and error process set out above, the present invention provides a process for testing femoral and tibial ligament origin points that is both accurate and minimally invasive. The procedure further utilizes a mock ligament and a tension isometer to measure, when the knee is flexed through a full range of motion, a change in tension of no more than a certain force verifying proper isometric selection of the femoral and tibial points of origin.